Outer joint part produced as a formed plate metal part

ABSTRACT

An outer joint part for a constant velocity universal ball joint, produced from a tubular member formed from a plate metal part and provided with substantially longitudinally extending ball tracks intended for receiving torque transmitting balls, with an axial central portion of the tubular member is reduced in cross-section relative to two axial end regions and is provided with ball tracks, with a substantially radial flange formed on at one axial end of the tubular member, with the center lines of the ball tracks extending in a non-parallel way relative to the axis A of the outer joint part and with the axial end of the tubular member positioned opposite the flange remaining undeformed.

This is a division of U.S. patent application Ser. No. 08/398,152 filedMar. 3, 1995, now U.S. Pat. No. 5,660,593 granted Aug. 26, 1997.

BACKGROUND OF THE INVENTION

The invention relates to an outer joint part for a constant velocityuniversal ball joint. The joint, is produced from a tubular memberformed from a plate metal part. The part has substantiallylongitudinally extending ball tracks intended to receive torquetransmitting balls. Constant velocity universal ball joints of this typeinclude the outer joint part described here and have a number ofcircumferentially distributed longitudinally extending ball tracks; aninner joint part with the same number of associated, circumferentiallydistributed, longitudinally extending ball tracks; torque transmittingballs received in the ball tracks associated with one another in theouter joint part and inner joint part; and a ball cage provided withcircumferentially distributed windows in which the balls areaccommodated individually and, in their entirety, held in one plane. Theball cage controls the balls on to the angle bisecting plane between theaxes of the outer joint part and the inner joint part.

An outer joint part intended for a constant velocity universal balljoint and produced from a tubular member as a formed plate metal part isknown from EP 2673128. The outer joint part, at one end, includes afirst end portion which, relative to the central portion, is formed intoa cylinder of a larger diameter. At the other end, the outer joint partincludes a second end portion reduced to form a cone. The completelyaxis-parallel ball tracks run into the deformed end portions at the twoends of the outer joint part. After the end regions with the changedcross-sections are formed, the ball tracks are formed radially outwardlyby a punch. The purpose of the formations at the two end regions is toavoid any cracks starting from the ends during the deformation processcarried out to form the ball tracks.

The above-described outer joint part is limited to constant velocityuniversal ball joints with completely axis-parallel ball tracks; itsdesign and production method do not allow it to be used for constantvelocity universal ball joints whose ball tracks are not completelyaxis-parallel.

SUMMARY OF THE INVENTION

It is an object of the present invention to propose an outer joint partproduced as a formed plate metal part, i.e. from a tubular member, and amethod of producing it. The outer joint part is suitable for constantvelocity universal ball joints whose ball tracks do not extend in acompletely axis-parallel way. The object is also to provide suitabletools for carrying out the method.

The objective is achieved by providing an axial central portion of thetubular member is reduced in cross-section relative to the two axial endregions and provided with ball tracks. Also a substantially radialflange is formed on at least one axial end of the tubular member.

In a particularly advantageous embodiment, the other axial end of thetubular member remains undeformed.

The embodiment in accordance with the invention ensures that, as aresult of the cross-section which is reduced relative to the originalcross-section, the material in the region of the ball tracks issubstantially strengthened, with the tracks running into the deformedand thus also strengthened flange region. The preferred embodiment alsoensures that the tracks do not extend as far as the other end of thetubular member so that here, too, there is no risk of any cracks beinginitiated from the axial end.

Various embodiments of the joint may be designed as follows:

that the center lines of the ball tracks are straight lines and form anangle of distal intersection with the axis of the outer joint part; thatthe center lines of the ball tracks extend helically and at a constantdistance relative to the axis of the outer joint part; that the centerlines of the ball tracks form at least two groups with different anglesof intersection or inclination relative to the axis of the outer jointpart; that the center lines of the ball tracks are curved outwardlyrelative to the central longitudinal axis of the outer joint part.

Track shapes of the above-mentioned type are of course known from thestate of the art. They all have in common and are in accordance with theinvention in that, if viewed axially, they are not undercut-free.

A method in accordance with the invention to produce the initiallymentioned outer joint part from a tubular member as a formed plate metalpart includes, during a first deformation stage, forming a flange byexpanding one end of a straight circular-cylindrical tubular portion;during a further deformation stage, preforming the ball tracks byentirely radially reducing an axial central portion above an inner tool;and a final deformation stage, calibrating the ball tracks by entirelyradially expanding the axial central portion against an outer tool.

In this way and by forming the flange it is possible, when forming theball tracks, to prevent the occurrence of cracks starting from therespective end edge of the tubular portion. On the other hand, byapplying entirely radial deformation methods, by avoiding drawingoperations, the risk of cracks forming as a result of shear stresses inthe surfaces is also largely avoided. The desired track shapes which areaxially not undercut-free can be achieved by advancing the respectivedeformation tools in an entirely radial direction.

To facilitate handling and simplify the tools, it is proposed, accordingto an advantageous embodiment of the invention, to make use of the twowider ends of the tubular member. Different parts of the inner tool,corresponding to the ball tracks, are introduced into the tubular memberfrom opposed axial directions. Following a radial deformation operation,the parts are pulled out of the tubular member from opposed axialdirections.

Especially for the purpose of producing ball tracks with differentangles of intersection or inclination relative to the axial direction,it is proposed that different parts of the inner tool corresponding tothe ball tracks are introduced from opposed axial directions into thetubular member while carrying out opposed helical movements and,following a deformation operation, are pulled out of the tubular memberin opposed axial directions while carrying out opposed helicalmovements.

A suitable device for carrying out the above-mentioned method inaccordance with the invention includes radially advancingcircumferentially distributed outer tools whose inner surface, in acomplementary way, represents the outer contour of the central portionof the outer joint part. Also, inner tools, which include a core partand finger parts and whose outer circumferential face, in acomplementary way, represents the inner contour of the central portionof the outer joint part, with the finger parts being positioned ingrooves of the core part and representing the track shape, are removedfrom the core part in the direction of their longitudinal extension.

In accordance to a further embodiment, two groups of finger parts withdifferent angles of intersection or inclination are removable from thecore part in opposed axial directions. Also, two groups of finger partsare each radially displaceably held in a finger holding part. Further, acore part is separated between two finger parts along radial planes intocircumferential segments. The part includes a central mandrel which hasa radial expanding effect on the circumferential segments, or thecentral mandrel includes a conical face which cooperates with innerconical portions at the circumferential segments.

From the following detailed description, accompanying drawings andsubjoined claims, other objects and advantages will become apparent tothose skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the invention will be described with reference to the drawingswhich illustrate the method of producing a preferred embodiment of anouter joint part in accordance with the invention in different stages bymeans of the outer and inner tools of the device in accordance with theinvention.

FIGS. 1a through 1f are partially in cross-section schematic views ofsix individual illustrations, which show the operations of forming on aradial flange and of reducing the central portion of an outer joint partin accordance with the invention.

FIGS. 2a through 2c are partially in cross-section schematic views ofthree individual illustrations, which show the operation of radiallycalibrating the central portion of an outer joint part in accordancewith the invention.

FIG. 2d is an elevation view of FIG. 2c of the joint part in a flattenedplane.

FIG. 3 is a cross-section view of the tool for reducing the centralportion in accordance with FIGS. 1c through 1e.

FIG. 4 is a cross-section view of the tool for radially expandingaccording to FIGS. 2a and 2b.

FIG. 5 is a partially in cross-section schematic view of anotherembodiment of the present invention including ball tracks curvedoutwardly with reference to the axis.

FIG. 6 is a partially in cross-section schematic view of anotherembodiment of the present invention with the ball tracks extendinghelically and at a constant distance relative to the axis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The individual illustrations of FIGS. 1a through 1f and 2a through 2cwill be described below, using the same reference numbers.

The individual illustrations of FIGS. 1a through 1f show phases of thefirst two-stage machining operation and a subsequent second machiningoperation carried out on the outer joint part.

FIG. 1a shows a straight cylindrical tubular member 1 on which themethod in accordance with the invention starts.

FIG. 1b shows the partially deformed tubular member 1' and 1"respectively, with deformation taking place in two phases in an entirelycylindrical die 2 which, on a base plate 3 with an annular projection 4,carries the tubular member. A first punch 5' is used to upset and form aradial flange 6', whereas a second punch 5" is used to complete theradial flange 6" which, hereafter, will only be referred to as flange 6.

FIG. 1c shows the outer joint part 11 which is deformed during a furtherstage and which includes the above-mentioned flange 6 and asubstantially undeformed axial portion 7 at the axially opposed end.Between the two axial end regions, a reduced central portion 8 isidentified which includes the ball tracks, as will be shown later.Between the flange 6 and the central portion 8 a conical region oftransition 9 is provided and between the undeformed portion 7 and thecentral portion 8 a portion of transition 10 is provided which is alsoconical. The operation of radially deforming the central portion 8 takesplace in a radially advancing circumferentially divided outer tool 12,while the tubular member 1 is simultaneously supported by a multi-partaxially divisible inner tool 13. The inner tool 13 includes a core part14 for the central portion 8 and parts 15 and 16 for the end portions 6,9 and 7, 10. Further details of the inner tool 13 whose parts 14, 15, 16are shown here in section will be identifiable in the following Figures.

FIG. 1d shows the outer joint part 11 after completion of its firstdeformation stage, with the parts of the outer tools 12 having beenremoved radially outwardly. Parts 14, 15, 16 are visible in a plan view,with the core part 14 still being in its position inside the outer jointpart 11, whereas the parts 15, 16 have been axially removed therefromwhile carrying out rotational movements. This figure shows that the corepart 14 of the inner tool is provided with grooves 17 which are engagedby, and support, finger parts 18 at the tool part 15 and finger parts 19at the tool part 16. The finger parts are inclined at different anglesrelative to the longitudinal axis. In view of the different angles ofinclination of each of the three finger parts 18, 19 on each of the toolparts 15, 16, also referred to as finger holding parts relative to oneanother, there occur, on the outer joint part, alternately differentlyinclined tracks whose axial run-out portions 20, 21, running into theconical regions of transition 9, 10, are already identifiable. Thefinger parts 18, 19 are slightly radially displaceable in the fingerholding parts 15, 16.

In FIG. 1e, the core part 14 of the inner tool 13 has also been axiallyremoved from the outer joint part 11. The grooves 17 in the core part 14are again shown with their longitudinal center line. Now the completetracks 22 are visible in the outer joint part 11 with their run-outportions 20, 21.

FIG. 1f shows the outer joint part 11 on its own after theabove-described stages of deformation, including the abovereferenceddetails.

To render the design of the tools more easily understandable, referenceis now made to FIG. 3. FIG. 3 shows a cross-section of the centralportion 8 of the outer joint part 11 in the configuration according toFIG. 1c. It shows the outer joint part 11 with formed track regions 22and reduced circumferential regions 23 positioned therebetween. Theouter joint part is supported by a circular-cylindrical core 14 of theinner tool which includes grooves 17 into which the finger parts 18, 19are inserted while carrying out rotating axial movements. The fingerparts are circumferentially alternately connected to one of the toolparts 15, 16. FIG. 3 also shows the outer tool 12 which, in acomplementary way, corresponds to the joined outer contour of the innertool 13 and which, in the section shown, is divided in radial planesthrough the centers of the finger parts 18, 19 and whose individualparts are moved in radially.

The individual FIGS. 2a through 2c show different phases of the finalmachining operation and are described below one after the other.

FIG. 2a shows the outer joint part 11 which corresponds to FIG. 1f.Reference is therefore made to the numbering of the various details.There is also shown an outer tool 32 which is circumferentially dividedand now radially supports the outer joint part from the outside. Aninner tool 33 which includes a core part 34 for the central portion 8,two parts 35 and 36 for the axial end portions 6, 9 and 7, 10 and theaxially feedable mandrel 43 is inserted into the outer joint part 11.The mandrel 43 includes a conical face 40 which cooperates with an innercone 41 of the core part 34. The core part 34 is circumferentiallydivided. By axially moving in the mandrel 43, the individual segments ofthe core part 34 of the inner tool 33 expand the central portion 8 ofthe outer joint part 11 against the supporting outer tool 32.

FIG. 2b shows that the circumferential parts of the outer tool 32 which,in this case, have a supporting function have been moved away radiallyoutwardly. Equally, the tool part 35 with the finger parts 38, whilecarrying out a rotational movement, has been disengaged from the outerjoint part 11 and the core part 34 and moved out. The core part 34 hasalready been axially pulled in the opposite direction, with the innertool 36 corresponding to the tool part 16 with the finger part 19 nolonger shown since it has previously been removed in the direction awayfrom the tool part 35 while carrying out an axial rotational movement.The tool parts 35, 36 are also referred to as finger holding parts. Thefinger parts 38 and the finger parts (not illustrated) corresponding tothe finger parts 16 are radially displaceably held in the tool parts 35,36. The outer joint part 11 now calibrated against the outer tool 32 isidentifiable with all its details as already shown in FIG. 1e.

The details are shown and numbered once again in FIG. 2con the outerjoint part, with the dimensions having changed only in the range of onetenth of a millimeter relative to the embodiment shown in FIG. 1f.

To render the tools used here more easily understandable, reference isnow made to FIG. 4 showing a cross-section through the outer joint part11 with the tools illustrated in FIG. 2a. The elements of the outerjoint part 11, the ball track portions 22 and intermediate portions 23,are also identifiable. With the exception of the dimensions, the partsof the outer tool 32 correspond to those of the outer tool 12 accordingto FIG. 3.

In the section shown here, the core part 34 is formed of circumferentialsegments 42 which adjoin one another with play in radial dividing planescentrally between two finger parts 38, 39. The finger parts 38, 39 whichare each circumferentially alternately connected to one of the fingerholding parts 35, 36 engage grooves 37 of the circumferential segments42. The conical mandrel 43 engages a central recess and when thesegments 42 advance axially, it presses radially outwardly for thepurpose of calibrating the track regions, with the outer joint part 11supported on the outer tool 32.

While the above detailed description describes the preferred embodimentof the present invention, the invention is susceptible to modification,variation, and alteration without deviating from the scope and fairmeaning of the subjoined claims.

We claim:
 1. A method of producing an outer joint part for a constantvelocity universal ball joint produced from a tubular member as a formedplate metal part and provided with substantially longitudinallyextending ball tracks intended to receive torque transmitting balls,comprising:forming a flange by expanding one end of a straightcircular-cylindrical tubular portion; pre-forming the ball tracks byradially reducing an axial central portion by means of radially inwardlymoving outer tools above a supporting inner tool; and calibrating theball tracks by radially expanding the axial central portion by means ofradially outwardly moving inner tools against a supporting outer tool.2. A method according to claim 1, comprising introducing different partsof the inner tool associated with the ball tracks from opposed axialdirections into the outer joint part and, following a deformingoperation, pulling said different parts out of the outer joint part inopposed axial directions.
 3. A method according to claim 2, comprisingintroducing different parts of the inner tool associated with the balltracks from opposed axial directions into the outer joint part whilecarrying out opposed helical movements and, following a deformingoperation, pulling said different parts out of the outer joint part inopposed axial directions while carrying out opposed helical movements.4. A device for producing an outer joint part comprising radiallyadvancable circumferentially separated outer tools whose inner composedsurface, in a complementary way, represents an outer contour of acentral portion and inner tools which include a core part and fingerparts being positioned in grooves of the core part and representing thetrack shape and being removable from the core part in the direction oftheir longitudinal extension; andtwo groups of finger parts withdifferent angles of distal intersection or inclination, with respect toa center longitudinal axis of said core part are removable from the corepart in opposed axial directions.
 5. A device according to claim 10,wherein two groups of finger parts are each radially displacably held ina finger holding part.
 6. A device according to claim 10, wherein a corepart is separated between two finger parts along radial planes intocircumferential segments and includes a central mandrel which has aradial expanding effect on the circumferential segments.
 7. A deviceaccording to claim 6, wherein the central mandrel includes a conicalface which cooperates with inner conical portions at the circumferentialsegments.